Prof. Dr. Samiran Chakrabarti
Biosystematics Research Unit, Department of Zoology, University of Kalyani, Kalyani 741 235, India e-mail: chakrabarti32b@vsnl.net
Exploration in the Indian territory reveals that the Himalyan mountain zones compared to that of other regions are very rich in aphid fauna. The Himalaya in general and western and northwest Himalaya in particular received special attention for such explorations due to the special geo-morphological and floral diversity of these zones. Aphids (Homoptera :
Aphididae) are one of the important pests of several agricultural, horticultural and forest plants besides their wild hosts. Many species are also potential vectors of several plant pathogens.
In the above two zones of the Himalaya as many as 246 aphid species under 142 genera and 10 subfamilies are known. The number of species constitutes 38% of the total Indian species known so far. Species under Aphidinae (119) are dominated here followed by
Pemphiginae (41) and Drepanosiphinae (27). Here, the representation of the species of
Hormaphidinae and Greenideinae are less as compared to the eastern or Assam
Himalaya. On the other hand, indigenous species are much more in these zones of the
Himalaya.
Diversity of gall forming aphids and their host diversity is more in these zones of the
Himalaya as compared to other himalayan zones and also other Indian localities. The study reveals that 72 species (29.46% of the total species of these zones) under 4 subfamilies viz., Aphidinae, Drepanosiphinae, Hormaphidinae and Pemphiginae are known to produce galls of different types on their host plants. Out of these, 37 species
(50.7%) are under the subfamily Pemphiginae and 31 species (43.05%) are under the subfamily Aphidinae.
Diversity in the life cycles of the above species, particularly those of gall forming species is more. Such diversity may be in respect either of omitting a particular morph in their polymorphic life cycle or omitting the sexual cycle or in the association of host plants.
Diversity of hosts of gall forming aphids is also wide. Forty-three host plant species under 24 families produce such aphid galls. The gall diversity indicates that species under the subfamilies Aphidinae, Drepanosiphinae and Hormaphidinae produce only leaf galls which are mainly leaf fold, leaf roll or spiral galls but those of Pemphiginae produce galls on leaf, petioles as well as on stems. Galls produced by different species are different in their locations, structures, textures and other morphology besides colours.